Abstract:
Factors responsible for the width of the stimulated emission spectrum of an XeCl laser are discussed. It is found that at high intracavity intensities ($\gtrsim 10$ MW/cm$^2$) the spectral width is governed by the deformation of the gain profile near the maximum due to weak saturation of the rate of rotational exchange. At fairly high input energies ($>0.2$ J/cm$^3$), heating of the active medium during a pump pulse shifts the gain maximum and this also broadens the spectrum obtained by time-integrated recording. The experimental data are in good agreement with the proposed analytic model.